In my STEAM project I discuss the pectus deformities.  The specific objectives my topic covers are: “know the stages of bone development and repair,” “know the parts of the bone and their shape,” and “explain how bone development is hormonally regulated.”  I chose this topic because it is close to my heart – actually, it’s further away from my heart – ba dum tss.  Since going through puberty I’ve had pectus carinatum (aka “pigeon” or “keel” chest), which is where the sternum and adjacent ribs protrude outward at an angle instead of continuing to grow in the typical orientation.  In extreme cases this resembles the chest of a bird, hence the name.  There are a few different types of pectus conditions, but I will specifically be focusing on pectus carinatum and excavatum due to their opposing nature.  I am also hoping to bring an awareness to these conditions; they’re more common than one may think, but are seldom discussed.

           Pectus excavatum (PE), also known as “funnel” or “sunken” chest is the counterpart to pectus carinatum (PC).  Instead of growing outward, the sternum and adjacent ribs are pushed inward, creating a funnel-shaped depression in the chest.  This is more common than the former (0.6% of the population), making up over 95% of chest abnormality cases and occurring in 0.1-2.6% of the population.  Both conditions are much more prevalent in males but are not unheard of in females (*raises hand*).  The sternum consists of 3 fused parts: the manubrium, gladiolus, and the xyphoid process, and their involvement or lack there-of can help classify the type and severity of the deformity (Koumbourlis, 2015). 

            The origins of pectus deformities are unclear, with some cases seemingly idiopathic (arising spontaneously with no known cause) and others syndromic (van Es, van Royen, & Oomen, 2022).  There is growing evidence pointing to them being inherited, and in several cases there is a distinct correlation between patients with a pectus deformity and a connective tissue disease, although the correlation is not consistent.  The pectus deformities are likely congenital, beginning while the sternum forms during the 6th week of gestation.  Any abnormalities in the surrounding cartilage are then exacerbated during the growth spurts of adolescence (Koumbourlis, 2015).  Often a pectus deformity tends to be accompanied by scoliosis, occurring in 5-21% of PE cases and 8-32% of PC cases (Ramadan et al., 2021), probably acting as the root cause of it.  The sternum indirectly connects to the spine through the ribs, so any deviation from the normal sternum alignment could put pressure on the thoracic spine and result in curvature, especially in asymmetric pectus deformities (Koumbourlis, 2015).

            PE and PC largely affect quality of life via decreased self-esteem, but symptoms in more severe cases can include chest pain and impaired cardiac function, as well as decreased pulmonary function for patients with PE due to their smaller thoracic cavity, equating to a lesser total lung volume (Ramadan, 2021).  There is no definite cure for PE or PC, but there are surgical and conservative options available for treatment.  For young patients with PE, undergoing the Nuss procedure after puberty has shown to be quite successful.  This is a minimally invasive surgical method that essentially involves placing a bar behind the sternum to correct its position (Brochhausen et al., 2012).  For patients with PC, orthotic braces have shown to be effective (Koumbourlis, 2015).

            For my piece I decided to construct three bonsai trees out of pipe cleaners, one representing the appearance of a ‘normal’ sternum, with the other two representing PE and PC.  Steps involved in growing a bonsai include constraining the roots with a small pot and wrapping the tree with copper wire to move and shape it.  After a few years, the tree will adopt the chosen shape and mature, in the end resembling an adult tree – just on a much smaller scale.  Though not a perfect metaphor, the wire that would be used to change the direction of growth for the tree represents the cause of PC or PE.  My project shows three trees – two that have been constrained at some point, and one that was left free to grow with nothing to change its standard shape.


Brochhausen, C., Turial, S., Müller, F. K., Schmitt, V. H., Coerdt, W., Wihlm, J. M., Schier, F., & Kirkpatrick, C. J. (2012). Pectus excavatum: history, hypotheses and treatment options. Interactive cardiovascular and thoracic surgery14(6), 801–806.

Koumbourlis, A. C. (2015). Pectus deformities and their impact on pulmonary physiology. Paediatric Respiratory Reviews16(1), 18–24.

Ramadan, S., Wilde, J., Tabard-Fougère, A., Toso, S., Beghetti, M., Vallée, J. P., Corbelli, R., Barazzone-Argiroffo, C., Lascombes, P., & Ruchonnet-Métrailler, I. (2021). Cardiopulmonary function in adolescent patients with pectus excavatum or carinatum. BMJ open respiratory research8(1), e001020.

van Es, L., van Royen, B. J., & Oomen, M. (2022). Clinical significance of concomitant pectus deformity and adolescent idiopathic scoliosis: systematic review with best evidence synthesis. North American Spine Society journal11, 100140.

One Comment

  1. Jenni discussed the pectus deformities pectus excavatum (PE) and pectus carinatum (PC) in her STEAM project. She covered the objectives, “know stages of bone development and repair”, “know the parts of the bone and their shape”, and “explain how bone development is hormonally regulated.”
    Pectus excavatum is an abnormal inward “funnel” depression in the chest, whereas pectus carinatum is an outward growth of the sternum and ribs, potentially resembling a bird, which is where the term “pigeon chest” comes from. Pectus excavatum is the far more popular of the two, making up around 95% of all chest deformities. PE and PC affect the ribs and the sternum, which is composed of the manubrium, gladiolus, and xyphoid process bones fused together. The causes of these deformities are unclear, but may be of inherited or idiopathic origin. PE and PC form in the womb as the sternum grows during the 6th week of gestation, and worsen during growth spurts as a child grows. PE and PC largely affect self-esteem, but may cause decreased pulmonary function, chest pain, or decreased cardiac ability in particularly detrimental cases. There is no cure, but the Nuss procedure and orthotic braces can help tremendously.
    Jenni modeled these pectus deformities by crafting bonsai trees out of pipe cleaners. For a regular chest she modeled an upright bonsai tree, while for pectus excavatum and carinatum she made bonsai trees with a concave and convex tree body respectively to represent the orientation of the sternum and ribs. Nice work!

    Stellen Johnson

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